Composite titanic-oxid pigment and method of producing same.



LOUIS E. BARTON, OF NIAGARA FALLS, NEW YORK, ASSI GNOR. TO THE TITANIUMALLOY MANUFACTURING COMPANY, OF NEW YORK, N. Y., A CORPORATION OF MAINE.

COMPOSITE TITANIC-0X11) PIGMENT AND METHOD OF PRODUCING SAME.

No Drawing.

1 b all whom it may concern:

Be it known that l, LOUIS E. BARTON, a citizen of the United States, anda resident of Niagara Falls, in the county of Niagara and State of NewYork, have invented certain new and useful Composite Titanic-OxidPigments and Methods of Producing the Same, of which the following is aspecification,

My present invention relates to substances, employed as pigments inpaint, and particularly to those containing important percentages oftitanic oxid. Its objects comprise provision of methods whereby, onindustrial scales, with economy and relatively slight technical skill orcare, such pigments are producible, substantially white in color and inwhich a given proportion of titanic oXid will produce its characteristicbeneficial eflects in a greater and more perfect degree than hitherto,particularly as regards the hiding power of the pigment when mixed asusual with oil and spread as paint. The increased hiding power thusimparted to oil paint by my novel composite titanic oxid pigments seemsattributable only to my novel methods of producing them, which result inan extremely, if not unprecedentedly, minute subdivision of the titanicconstituent and its peculiar attachment to, or coalescence with,suspended minute particles of a sulfate base, or extender, usuallypreponderating, but which has, however, by itself, in oil, no hidingpower; and I am satisfied thatequally good results are unattainablethrough any mere mechanical mixing of the same or even greaterproportions of any titanic material withsimilar bases otherwiseproduced,

lit is known that soluble salts of the alkali-- earths react withsolutions of sulfates to form precipitates of insoluble sulfate; and itis also known that acid solutions of titanic acid when much diluted andboiled precipi- Specification of Letters Patent.

' Application filed July 14, 1914:- Serial No. 850,876. to l .i 3

Facet. 5, 11%;5.

' insoluble sulfate, be added, and the precipiaccelerated and the yieldgreatly increased notwithstanding the high concentration of thesolution; and furthermore the titanic oxid under these conditions isprecipitated in an extremely fine state of division and seems to attachitself to the suspended par-' tioles of sulfate base in a manneranalogous to that in which organic coloring matter, precipitated fromsolution, attaches to suspended particles, in the preparation oflakepigments for example. The product resulting from my said discoveryappears to be in the nature of an adsorption-compound, or a coalescenceof colloidal titanic acid and sulfate particles.

My methods are practised and my novel composite products attained asfollows :-I first obtain, in any convenient manner, a titanic sulfatesolution, as free from impurities as possible. I can use anytitaniferous material which can be brought into sulfuric acid solution,as, for example, titaniferous iron ore, or ilmenite, dissolved insulfuric acid, or first fused with alkali compounds and subsequentlydissolved in sulfuric acid, but I prefer to use, on account of theircomparative freedom from objectionable impurities, such as iron oxid,and also because they are so easily dissolved by sulfuric acid, thedried, uncalcined, products resulting from either of the proceduresjointly'invented by Auguste J. Rossi and myself, for which have beengranted to us Letters Patent No. 1,106,409 and No. 1,106,410, both datedAugust 11, 1914, and for which is still pending our application SerialNo. 8410,19? filed May 22, 1914.

By our said procedures the desired solution is, generally speaking,obtained by aid of melting titanic oxid together with sulfid ofan alkalimetal, or with sulfate of an alkali metal and carbon, lixiviating, ornot, the resulting lute sulfuric acid :the resulting dried productsconsist preponderatingly of t1- melts and boiling them in difate.

tanic oxid in the form of soft, gray, powder, their constituentsbeing,-as shown by analyses, .variable within the follor. ing limits,

viz:

Titanic oxid 65 to 80% H Silica lto 5 Iron oxid; lto 7 Soda 2to 15Sulfur (free) lto 15 Sulfuric anhydrid t, to 1 Preferably such atitaniferous material, or titanic oxid concentrate, I digest at atemperature of 100 C. to 150 C. in an iron, or other refractory, vesselwith 95% sulfuric acid in the proportionof 2.5 to 2.6 parts, by weight,of sulfuric acid to one part by weight of the titanic oxid. I continuethe digestion until a sample taken from the digester shows by analysis apractically complete combination of the sulfuric acid with the bases.Under these conditions 85% to 95% of the titanic oxid of the charge willbe combined with sulfuric acid as titanic sulfrom the digester to alead-lined, or other, refractory vessel and therein dissolve them inWater, the volume of which is about three times that of the sulfuricacid used in the charge. The resulting solution is of suitableconcentration for filtration fromlany undissolved residue and ofconvenient volume for storage; To say 1 10 parts, by weight, of thistitanic sulfate solution having a specific gravity of about 1.40 andcontaining approximately 15% titanic oxid, I add a solution, preferablyhot, of about 40 parts of calcium chlorid, the exact chemicallyequivalent quantity of calcium chlorid being calculated from the totalsulfuric acid as determined by analysis of the titanic sulfatesolution,and the volume of the mixed solutions made up by additions ofwater to three times that of the titanic sulfate solution used. Thismixed solution containing, immediately precipitated, suspended, calciumsulfate I then treat in any convenient manner so as topromoteprecipitation therein of titanic acid, as, for example, bydigesting it at about 100 C. for five to eight hours in a closed vessel,preferably connected with a reflux condenser by which any'small quantityof acid vapor is returned to the digester. The completion of thedigesting operation can be determined by withdrawing a sample of thecharge and determining approximately the percentage of titanic oxidremaining in solution. 1 next filter out the composite precipitatedproduct, wash it with cold water, dry it and calcine it at a red heatuntil free from volatile matter ('7: c.

. combined water) a The result of all the operations, including I Thismass of materials I then remove menace calcination, may be indicated bythe following equation, viz

Pigment product. 4H0},

From this equation the theoretical composition of the product is:

Titanic oxid (TiO 23.42 Calcium sulfate (CaSOQ 76.58%

Titanic oxid 15 to 25% Calcium sulfate 7 5 to 85% and that the specificgravity varies from 2.95 to 3.10 depending on composition.

It will be noted that as a result of calcination the calcium sulfateconstituent of the product is the anhydrous form and not the hydratedvariety hitherto used in pigments as an extender.

A complete analysis of one lot of my product showed the compositionTitanic oxid 23.92% Calcium sulfate 75.57

, Tron oxid .18

' Soda .12 Chlorin Trace Loss upon ignition- .08

Specific gravity 3.07

As to my resulting final composite titanic oxid products the followingcharacteristics,

are notable, viz: Their titanic oxid constituents are White, amorphous,or non-crystalline, and, I believe, chemically uncombined with othersubstances. Their calcium sulfate constituents are anhydrous and in theform of exceedingly minute crystals, their dehydration beingattributable to their calcination, and their exceptional minutenesslikewise attributable to calcination-and also, I believe, to thecolloidal character of the solution and precipitation therein occurring.

To these very minute calcium sulfate particles are externally adherentthe said amorphous titanic oxid, thus imparting to them and so also tomy composite pigments, as a whole, their hiding power and otherdesirable qualities.

Some of the foregoing characteristics of my pigments are discernible byaid of the microscope; also by examination under polarized light; in thelatter case the larger, z. e. sulfate, particles appearing luminousnuisance and characteristically coated with the smaller particles ofrelatively opaque titanic oxid. I My composite titanic oxid pigment istherefore, when produced by aid of calcium chlorid, as aforesaid,characterizable and distinguishable as comprising titanic oxid and asulfate, usually in the proportion of from 15% to of the former to 75%to 85% of the latter; and as containing also, usually, iron oxid, sayfrom traces to 25%; as of specific gravity say from 2.95 to 3.10; and asbeing, after calcination, a soft, very fine powder, in color whitefaintly tinged with cream; as containing sulfate particles in minutecrystalline form and amorphous titanic oxid particles in still moreminute form coalesced with, or more or less coating, said sulfateparticles, 71. e. adhering to the latter externally.

The exceptional merits of my composite titanic pigments will beappreciated from the fact that notwithstanding they contain suchcomparatively low percentages of titanic oxid' possessing hiding power,and such much greater percentages of a sulfate which of itself has nohiding power, their hiding power when mixed with oil for paint is fullyequal to that of pigments containing 100% of the previously employedlead or zinc compounds.

I can hasten the operation, in some cases, if desired, by stirring, oragitating, occasionally the solution thus hastening the reactions. I canalso, if in some cases thought advisable to increase the yield ofproduct from a given charge, accomplish this by the following variationsin the process heretofore described, viz: To my above described titanicsulfate solution of 1.40specific gravity, containing about 15% titanicoxid and variable small percentages of iron and sodium sulfates withlittle, or no, free sulfuric acid, I add a saturated solution of thechlorid, as of calcium, both solutions being preferably, though notnecessarily, hot when thus mixed. In treating this mixed solution, topromote precipitation of titanic acid, 1, instead of digesting,evaporate, or distil, it, at about 100 (3., with the result that thetitanic acid is, by these equivalent means, precipitated, as before, onthe precipitated calcium sulfate. Any escaping hydrochloric acid may, ifdesired, be condensed and recovered as a by-product. I conduct the saidevaporation, or distillation, like the before described digestion, at atemperature of about 100 C. because I find that at this comparativelylow temperature the iron chlorid which, if any, may separate meanwhile,is not decomposed but remains in crystalline form readily soluble inwater. I prefer to conduct the distillation in a vacuum still becausethis permits rapid operation at comparatively low temperatures, and itwill, of course, be understood that this, as well as all apparatusinvolving manipulation of the acid solutions, must be refractory tohydrochloric acid, a. e. stoneware for example.

Ihe residue in the still I take up with from eight to ten times itweight of hot Water and digest it for a short time suficient tocompletely dissolve ferric salts. I then filter, wash the precipitatethoroughly with water, and dry it and calcine it at a red heat as beforedescribed.

Though the yield of product from a given charge is in some casesconsiderably increased by these variations of my process, I regard it aspossible that this advantage may be more frequentlyoflset by thecomparative complexity and expenses of operatlon and apparatus involved,but inasmuch as, for some purposes, its said variations may enhance itsutility I have described them here in order that there may be a completeunderstanding of all the ways, now known to me, in which my inventioncan be used. In this connection it is proper to add that I have alsodiscovered that the titanic oxid content of my final product can, if sodesired for certain purposes, be somewhat increased by a preliminaryfiltering of the mixed solution made after the addition of a part of thechlorid, the remainder of the chlorid being added to the filtrate. Thisis due to the fact that most of the-resulting insoluble calcium sulfateprecipitates in ad- :nce of the precipitation of the titanic acid, hencesuch preliminary filtration serves to separate from the solution aportion of the sulfate before titanic acid is thereon precipitated andthus correspondingly decreases the percentage of sulfate and increasesthe percentage of titanic oxid in the final calcined product, otherwisethe operations are conducted as before described.

My researches have also demonstrated that chlorid of barium isparticularly well adapted as a substitute for chlorid of calcium in theoperation of my method, and with similar, if not equal, results, butthis I reserve for another application for patent.

Having now described my invention, what I claim as new and desire tosecure by Let ters Patent is the following, v1z:

. to a soluble salt capable of forming by reaction with said solution aninsoluble sul fate and digesting the mass so as to produce acompositeprecipitate comprising such insoluble sulfate and titanic acid.

3. The method of treating a titanic sulfate solution which comprisesadding thereto a chlorid of an alkali earth metal and digesting the massso as to produce a compositeprecipitate comprising an insoluble sulfateand titanic acid.

4:. The method of treating a titanic sulfate solution which comprisesadding thereto chlorid of calcium and digesting the mass so as toproduce a composite precipitate comprising an insoluble sulfate andtitanic acid.

5. The method of making pigments containing titanic oxid which comprisesdigesting a titanic compound'in sulfuric acid until titanic sulfate isformed, adding a compound capable of forming an insoluble sulfate,treating the mixture to promote precipitation of titanic acid,separating the resuiting precipitates, and calcining them.

6; 'ihe methodof making pigments containing titanic oxid which comprisesdigesting a titanic compound in sulfuric acid until titanic sulfate isformed, adding chlorid of calcium, treating the mixture to promoteprecipitation of titanic acid, separating the resulting precipitatesfrom the solution, and calcining them.

7. In the production of pigments containing titanic material the stepswhich consist in adding to a titanic sulfate solution a saturatedsolution of a compound capable of forming by reaction with said solutionan insoluble sulfate and digesting the mass so as to produce a compositeprecipitate.

8. In the production of pigments contain ing titanic material the stepswhich consist in adding to a titanic sulfate solution a saturatedsolution of chlorid of cilcium and digesting the mass so as to produce acomposite precipitate.

9. In the production of pigments containing titanic oxid the steps whichconsist in adding to a titanit sulfate solution a. solution of a solublesalt capable of forming by reaction with said solution an insolublesulfate, and digesting the mixture at about 100 C. until an insolublesulfate and titanic acid have been precipitated.

10. In the production of pigments containing titanic oxid the stepswhich consist in adding to a titanic sulfate solution a so-.

lution of chlorid of calcium, and digesting the mixture at about 100 C.until insoluble sulfate of calcium and titanic acid have beenprecipitated.

11. In the production of pigments containing titanic oxid the stepswhich consist menace the resulting mixture at about 100 (1., di-

gesting the residue in hot water, separating the resulting precipitatesfrom the solution and calcining them. I

12. In the production of pigments containing titanic oxid the stepswhich consist in adding to a titanic sulfate solution a solution ofchlorid of calcium, distilling or evaporating the resulting mixture atabout 100 (1, digesting the residue in hot water, separating theresulting precipitates from the solution and calcining them.

13. In the production of pigments containing titanic oxid the stepswhich consist in adding to a titanic sulfate solution aprecipitant-compound capable' of forming by reaction with said solutionan insoluble sulfate, filtering the resulting solution to separatetherefrom then-precipitated particles of said insoluble sulfate, addingmore of said precipitant-compound to the filtrate, and

of calcium, filtering the resulting solution to separate therefromthen-precipitated particles of calcium sulfate, adding more chlorid ofcalcium to the filtrate and. separating therefrom precipitated particlesof calcium sulfate and of titanic acid.

15. As a new article a composite pigment comprising titanic oxid and asulfate extender.

16. As a new article a composite pigment comprising titanic oxid andmore of a sulfate extender.

17. As a new article a composite pigment comprising a sulfate extenderand, thereto adhering, titanic oxid.

18. As a new article a composite pigment comprising particles of asulfate extender and thereto adhering smaller particles of tiv tanicoxid.

19. As a new article a composite pigment comprising titanic oxid, asulfate extende c,

and iron oxid. 4 I

20. As a new article a composite pigment comprising particles of asulfate extender, thereto adhering smaller particles of titanic oxid,and comprising also iron oxid in quantity less than said titanic oxid.

21. As a new article a composite pigment comprising titanic oxid andcalcium sulfate.

22. As a new article a composite pigment comprising titanic oxid andmore calcium sulfate.

23. As a new article a composite pigment msaaea comprising calciumsulfate and thereto adhering titanic oxid.

24. As a new article a composite pigment comprising particles of calciumsulfate and thereto adhering smaller particles of titanic oxid.

25. As a new article a composite pigment comprising titanic oxid,calcium sulfate in quantity greater, and iron oxid in quantity less,than said titanic oXid.

26. As a new article a composite pigment of specific gravity 2.95 to3.10 in the form of a soft, fine powder, in color white faintly tingedwith cream, and consisting principally of particles of calcium sulfatehaving w thereto adherent smaller particles of titanic oxid.

27. As a new article a composite pigment of specific gravity 2.95 to 3.0 in the form of a soft, fine powder, in color white faintly 2a tingedwith cream, consisting principally of particles of calcium sulfate,having thereto adherent smaller particles of titanic oxid, andcontaining also iron oXid.

LOUIS E. BARTON. Witnesses:

WM. V. KNoWLEs, C. J. KINZIE.

